Breakaway bail

DETAILED DESCRIPTION What is claimed is: 1.
An arrangement for assuring a preferred mode of failure for a crane mounted on a pedestal when subjected to an overload comprising: an upper rotatably mounted on said pedestal; a boom pivotally attached to said upper; a pulley rotatably mounted on said boom; a hoist winch mounted on said upper; a first wire rope trained over said pulley and wound on said hoist winch; a hook suspended from said first rope, the mounting of said upper on said pedestal being capable of withstanding a maximum design load moment applied to said hook; a gantry secured to said upper; a boom winch mounted on said upper; a second wire rope wound on said boom winch and extending between said boom and said gantry to control the angle of said boom; bushing means attached to tension plate means for pivotally attaching said tension plate means to said gantry; a multiple sheave pulley attached to said plate means over which said second wire rope is trained; and said tension plate means having a reduced cross-sectional area which creates tension stresses sufficient to cause separate of said plate means at a load moment less than said design load moment.
2.
The invention according to claim 1 wherein said tension plate means consists of a pair of parallel tension plates and further comprising: a spacer tube secured between said plates and aligned with said bushing means; a pin engageable with said bushings for pivotal attachment of said bail to said gantry; a transverse beam having an upright flange affixed between said plates; brackets secured to the said beam for mounting said pulley; and each of said plates having upper and lower curved surfaces between said flange and said tube to define said reduced cross-sectional area.




Description:
This invention relates to pedestal mount cranes, and more particularly, to bails for use with such crane.
The present invention provides a bail for a crane, especially for pedestal mount cranes intended for use on offshore platforms, which permits a predetermined and preferred mode of failure